Differential rectifier for use in a wireless power receiver, and method of rectifying a power signal
A differential rectifier for use in a receiver for receiving wireless power via inductive coupling comprises first and second capacitors; first and second switching elements; and first and second inductors. The first capacitor and first inductor are electrically connected in series, and the second capacitor and second inductor are electrically connected in series. The first switching element is electrically connected between the first capacitor and first inductor in parallel, and the second switching element is electrically connected between the second capacitor and second inductor in parallel. The first capacitor electrically is connected to a terminal of a coil for receiving power wirelessly via inductive coupling, and the second capacitor is electrically connected to another terminal of a coil for receiving power wirelessly via inductive coupling. The first and second switching elements are electrically connected to a tap of a coil for receiving power wirelessly via inductive coupling.
1 . A differential current-driven rectifier for use in a receiver for receiving wireless power via inductive coupling, the differential current-driven rectifier comprising:
a first capacitor and a second capacitor;
a first switching element and a second switching element;
a first inductor and a second inductor; and
a third capacitor for dampening or reducing voltage ringing at the differential current-driven rectifier,
the first capacitor and the first inductor electrically connected directly to a first node, and the second capacitor and the second inductor electrically connected directly to a second node;
the first switching element electrically connected to the first node between the first capacitor and the first inductor, and the second switching element electrically connected to the second node between the second capacitor and the second inductor;
the first capacitor electrically connected between a terminal of a coil for receiving power wirelessly via inductive coupling and the first node, and the second capacitor electrically connected between another terminal of the coil for receiving power wirelessly via inductive coupling and the second node;
the first switching element and the second switching element electrically connected to a tap of the coil for receiving power wirelessly via inductive coupling;
the third capacitor electrically connected to one of the first switching element and the second switching element via a third node, and electrically connected directly to one of the first node and the second node, wherein the third capacitor has a capacitance equal to
C
=
0.175
wR
Load
,
where C is the capacitance of the third capacitor,
where w is a frequency of operation of the differential current-driven rectifier, and
where R Load is a resistance of an output load connected to the differential current-driven rectifier; and
the first inductor and the second inductor electrically connected to a fourth node at which a constant DC current is provided.
2 . The differential current-driven rectifier of claim 1 , wherein the third capacitor is electrically connected to the first switching element via the third node and directly to the first node.
3 . The differential current-driven rectifier of claim 2 , further comprising a fourth capacitor electrically connected to the second switching element via the third node and directly to the second node, wherein the fourth capacitor has a capacitance equal to
C
=
0.175
wR
Load
,
where C is the capacitance of the fourth capacitor,
where w is the frequency of operation of the differential current-driven rectifier, and
where R Load is the resistance of the output load connected to the differential current-driven rectifier.
4 . A receiver for use in a wireless power transfer system, the receiver for receiving power via inductive coupling, the receiver comprising:
the differential current-driven rectifier of claim 1 ; and
a coil for extracting power from a generated field via inductive coupling.
5 . The receiver of claim 4 , wherein
the first capacitor and the first inductor are electrically connected directly to the first node with the first switching element electrically connected to the first node between the first capacitor and the first inductor, and/or
the second capacitor and the second inductor are electrically connected directly to the second node with the second switching element electrically connected to the second node between the second capacitor and the second inductor.
6 . The receiver of claim 4 , further comprising at least one additional inductor electrically connected to the one of the terminals or the tap of the coil.
7 . The receiver of claim 4 , further comprising a fourth capacitor electrically connected to the fourth node between the first inductor and load electrically connected to the differential current-driven rectifier, the fourth capacitor for filtering a power signal output by the differential current-driven rectifier.
8 . The receiver of claim 4 , wherein the coil comprises at least two windings,
an outer turn of a first winding and an inner turn of a second winding forming a first sub-coil of the coil, and
an inner turn of the first winding and an outer turn of the second winding forming a second sub-coil of the coil.
9 . The receiver of claim 8 , wherein a first terminal is formed at a termination of the outer turn of the first winding or the inner turn of the first winding, and a second terminal is formed at a termination of the outer turn of the second winding or the inner turn of the second winding, and
wherein the tap is formed between the first terminal and the second terminal to split the coil into the first sub-coil and the second sub-coil.
10 . The receiver of claim 9 , wherein the differential current-driven rectifier is a synchronous rectifier,
the first switching element is a first transistor, and the second switching element is a second transistor, and
the differential current-driven rectifier further comprising:
the first transistor electrically connected to the tap of the coil and the first terminal of the coil; and
the second transistor electrically connected to the tap of the coil and the second terminal of the coil.
11 . The receiver of claim 10 , further comprising:
a first signal generator electrically connected to the first transistor for generating a pulse signal to drive the first transistor;
a second signal generator electrically connected to the second transistor for generating a pulse signal to drive the second transistor;
a first delay line electrically connected to the first terminal of the coil, the first delay line for synchronizing operation of the first transistor; and
a second delay line electrically connected to the second terminal of the coil, the second delay line for synchronizing operation of the second transistor.
12 . A method of rectifying a power signal received at a receiver of a wireless power transfer system, the method comprising:
extracting power from a generated field via inductive coupling at a coil to generate an AC power signal; and
rectifying, with a differential current-driven rectifier, the AC power signal, the differential current-driven rectifier comprising a first capacitor and a second capacitor; a first switching element and a second switching element; a first inductor and a second inductor; and a third capacitor for dampening or reducing voltage ringing at the differential current-driven rectifier,
the first capacitor and the first inductor electrically connected directly to a first node, and the second capacitor and the second inductor electrically connected directly to a second node;
the first switching element electrically connected to the first node between the first capacitor and the first inductor, and the second switching element electrically connected to the second node between the second capacitor and the second inductor;
the first capacitor electrically connected between a terminal of the coil for receiving power wirelessly via inductive coupling and the first node, and the second capacitor electrically connected between another terminal of the coil for receiving power wirelessly via inductive coupling and the second node;
the first switching element and the second switching element electrically connected to a tap of the coil for receiving power wirelessly via inductive coupling;
the third capacitor electrically connected to one of the first switching element and the second switching element via a third node, and electrically connected directly to one of the first node and the second node, wherein the third capacitor has a capacitance equal to
C
=
0.175
wR
Load
,
where C is the capacitance of the third capacitor,
where w is a frequency of operation of the differential current-driven rectifier, and
where R Load is a resistance of an output load connected to the differential current-driven rectifier; and
the first inductor and the second inductor electrically connected to a fourth node at which a constant DC current is provided.